Process for preparing autotype-negatives.



No. 802,598. PATBNTED 00T. 24, 1905. G. RICHTER. PROCESS POR PREPARIISYG AUTOTYPE NEGATIVES.

APPLICATION FILED MAYI, 1905.

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(QA/MVM E MQW M UNITED STATES PATENT OFFICE.

PROCESS FOR PREPARING AUTOTYPE-NEGATIVES.

Specicaton of Letters Patent.

- Patented Oct. 24, 1905.

Application filed May 4,1905. Serial No. 258,854.

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Be it known that I, CARL RICHTER, a citizen of the German Empire, and a resident of Bremen, Germany, have invented certain new and useful Improvements in Processes l'or Preparing Autotype-Negatives, of which the following is a speciiication.

The object of this invention is to clear the lights of autotype or photomechanical printing-plates, in which, as is well known, the ordinary printing process leaves small points on the surface where these surfaces ought to be perfectly white, this clearing' being effected by means of a subsequent exposure of the negative to light through a second screen of a diierent kind.

In the accompanying drawings, Figure l represents the first or cross screen used in my improved process. Fig. 2 represents the sec ond or point screen. picture to be reproduced. Fig. la represents the negative of said picture when produced 'by the iirst screen only, and Fig. 2 represents said negative when produced by both screens.

Brieily stated, the object of the invention is to reduce the openings of the negative shown in Fig. la to about one-half at the light portions of the picture.

The process consists in systematically removing the single elements which the crossscreen, Fig. l, leaves in the lights of the picture-c1 e., in the shadows of the negative, Fig. l, To this effect the negative after being exposed to the cross-screen is exposed to the action of a point-screen, Fig. 2, in which the distance between the centers oi' the covered elements is equal to double the distance between the centers of the openings in the crossscreen. Thus a process-negative prepared in the ordinary way in a screen-camera bei'ore Fig. 3 represents the being developed is subjected to a short second exposure after the cross-screen has been replaced by a point-screen. In this way the lights of the negative are 'further exposed, but only at those places which are not protected by the covered parts of the point-screen. A copy prepared by this negative, Fig. 2, appears in the deep portions like one prepared by the ordinary screen process; but the number oi' printing elements in the lights is reduced by one-half, so that a much deeper etching oi the plates is rendered possible.

Vhat I claim is l. A process vof preparing autotype-negatives which consists in iirst exposingthe negative through a cross-screen and then exposing' it through a screen provided, at the points corresponding to the openings of the crossscreen, with uniformly-alternating covered and uncovered elements, substantially as speciiied.

2. A process olI preparing' autotype-negatives which consists in iirst exposing the negative through a cross-screen and then exposing it through a point -screen, substantially as specified.

3. A process of preparing autotype-negatives which consists in iirst exposing the negative through a cross-screen, and then exposing it through a point-screen, the distance between the centers oi' the covered elements of the point-screen, corresponding to double the dis tance between the centers of the openings of the cross-screen, substantially as speciiied.

Signed by me at Bremen, Germany, this 22d day of April, 1905.

CARL RICHTER. l/Vitnesses:

WV. SHEELE, GG. JANssnN. 

